History: Mogre Tutorial - Embedding Mogre in Windows.Forms

Source of version: 7 (current)

Original version by [http://www.idleengineer.net|Clay Culver] 

Any problems you encounter while working with this tutorial should be posted to the [http://www.ogre3d.org/phpBB2addons/viewforum.php?f=8|Mogre Forums].

{maketoc}

!!Prerequisites
This tutorial assumes you have knowledge of C# programming and are able to setup and compile an Mogre application (if you have trouble setting up your application, see ((Mogre Basic Tutorial 0)) for a detailed setup walkthrough). It also assumes that you know the basics of Windows.Forms usage. Additionally, his tutorial directly builds on the previous tutorial, so you should work through that one before starting on this one.

!!Introduction
In this tutorial I will be walking you through how to embed Ogre in a Windows.Forms window. A word of caution, in previous tutorials we have put all of our code into a single file (wrapped in a single namespace). In this tutorial you will probably be working with multiple files. If you receive errors in your program the first thing you should check is to make sure that all namespaces match up.

As you go through the tutorial you should be slowly adding code to your own project and watching the results as we build it.

!!Getting Started
Unlike the previous tutorials, we will not be starting from a compilable code base. Be sure to follow these instructions carefully and make sure that at the end of this section you are able to run the program before continuing.

!!!The Main Function
Create a new Mogre project and clear out all of the contents of it. Create a new file (called program.cs) and add the following to it:

{CODE(wrap="1", colors="c#")} using System;
 using System.Collections.Generic;
 using System.Windows.Forms;
 
 namespace Tutorial06
 {
     static class Program
     {
         [STAThread]
         static void Main()
         {
             OgreForm form = new OgreForm();
             form.Init();
             form.Go();
         }
     }
 }
{CODE}
!!!The Form


In Visual Studios, right click on your project, click on Add, then "Windows Form...". Name the file "OgreForm.cs". Add two methods to this class, __Go__ and __Init__:

{CODE(wrap="1", colors="c#")}        public void Go()
        {
        }
 
        public void Init()
        {
        }
{CODE}
If you are using something other than Visual Studio to create this program, add a new class which derives from System.Windows.Forms.Form. We will not be using any Visual Studio's specific features in this tutorial, so you should not really have to do any translation.

!!!Running the Application
Make sure you can compile and run the application before continuing. If you are having difficulty, refer to the ((Mogre Basic Tutorial 0|project setup guide)) or post to [http://www.ogre3d.org/phpBB2addons/viewforum.php?f=8|the forums]. Note that this program should do nothing until we add further code to it.

If you run into problems which say something similar to: ''The type or namespace name 'OgreForm' could not be found (are you missing a using directive or an assembly reference?)'' then you probably have a namespace problem. Check to make sure that the "namespace" directive which wraps "program.cs" is the same as the one which wraps your form.

!!The Init Function
The ''Init'' function for our program will be very similar to the ''Init'' function in the previous tutorial. With the exception of the RenderWindow creation, we will not go into much detail about it since you should have already seen these concepts in the last tutorial. Before we add code to the ''Init'' function, we need to create an instance variable to hold the root object. At the beginning of the ''OgreForm'' class, add the following code:

{CODE(wrap="1", colors="c#")}        Root mRoot;
        RenderWindow mWindow;
{CODE}
Now we can add the following code to the ''Init'' function in the ''OgreForm'' class:

{CODE(wrap="1", colors="c#")}            // Create root object
            mRoot = new Root();
 
            // Define Resources
            ConfigFile cf = new ConfigFile();
            cf.Load("resources.cfg", "\t:=", true);
            ConfigFile.SectionIterator seci = cf.GetSectionIterator();
            String secName, typeName, archName;
 
            while (seci.MoveNext())
            {
                secName = seci.CurrentKey;
                ConfigFile.SettingsMultiMap settings = seci.Current;
                foreach (KeyValuePair<string, string> pair in settings)
                {
                    typeName = pair.Key;
                    archName = pair.Value;
                    ResourceGroupManager.Singleton.AddResourceLocation(archName, typeName, secName);
                }
            }
 
            // Setup RenderSystem
            RenderSystem rs = mRoot.GetRenderSystemByName("Direct3D9 Rendering Subsystem");
                                                // or use "OpenGL Rendering Subsystem"
            mRoot.RenderSystem = rs;
            rs.SetConfigOption("Full Screen", "No");
            rs.SetConfigOption("Video Mode", "800 x 600 @ 32-bit colour");
 
            // Create Render Window
            mRoot.Initialise(false, "Main Ogre Window");
            NameValuePairList misc = new NameValuePairList();
            misc["externalWindowHandle"] = Handle.ToString();
            mWindow = mRoot.CreateRenderWindow("Main RenderWindow", 800, 600, false, misc);
 
            // Init resources
            TextureManager.Singleton.DefaultNumMipmaps = 5;
            ResourceGroupManager.Singleton.InitialiseAllResourceGroups();
 
            // Create a Simple Scene
            SceneManager mgr = mRoot.CreateSceneManager(SceneType.ST_GENERIC);
            Camera cam = mgr.CreateCamera("Camera");
            cam.AutoAspectRatio = true;
            mWindow.AddViewport(cam);
 
            Entity ent = mgr.CreateEntity("ninja", "ninja.mesh");
            mgr.RootSceneNode.CreateChildSceneNode().AttachObject(ent);
 
            cam.Position = new Vector3(0, 200, -400);
            cam.LookAt(ent.BoundingBox.Center);
{CODE}
There are two new things we have done since the last tutorial. The first change is in how the RenderWindow is created. Here is that section of code again:

{CODE(wrap="1", colors="c#")}            mRoot.Initialise(false, "Main Ogre Window");
            NameValuePairList misc = new NameValuePairList();
            misc["externalWindowHandle"] = Handle.ToString();
            RenderWindow window = mRoot.CreateRenderWindow("Main RenderWindow", 800, 600, false, misc);
{CODE}
To embed Ogre into a window which you create (as opposed to letting Ogre create its own window), you have to create a render window manually with Root's CreateRenderWindow function. We supply the Form's Handle to Ogre in the NameValuePairList parameter so that Ogre knows what window to render inside of. You can create multiple render windows this way, and you don't have to use a Form to render Ogre inside of. You may also use other types of controls (such as UserControl) to host Ogre.

The second thing we have changed is we set the AutoAspectRatio of the Camera function:

{CODE(wrap="1", colors="c#")}            cam.AutoAspectRatio = true;
{CODE}
We will cover the reason for this change in the next section.

!!The Constructor and Event Handlers
There are two things we need to do in the constructor of our class. The first is to set the size of our Form to be 800 x 600. The second is to register event handlers for the Disposed and Resize events. Find ''OgreForm''~np~'s~/np~ constructor and add the following code to the very end:

{CODE(wrap="1", colors="c#")}            this.Size = new Size(800, 600);
            Disposed += new EventHandler(OgreForm_Disposed);
            Resize += new EventHandler(OgreForm_Resize);
{CODE}
When the form closes, we need to make sure that we cleanup our Root object (and also ensure that the render loop is no longer running). To do this, we will call the Root Object's Dispose method and setting the variable to null:

{CODE(wrap="1", colors="c#")}        void OgreForm_Disposed(object sender, EventArgs e)
        {
            mRoot.Dispose();
            mRoot = null;
        }
{CODE}
Whenever the form is resized, we need to inform the RenderWindow of the new size:

{CODE(wrap="1", colors="c#")}        void OgreForm_Resize(object sender, EventArgs e)
        {
            mWindow.WindowMovedOrResized();
        }
{CODE}
Since we set the AutoAspectRatio property of our Camera to be true (see the previous section), every time the window is resized, the Camera will be automatically updated to avoid stretching of the scene. Had we left that property to be the default value (false), the scene would strech whenever the window is resized.

In this tutorial, we have set the resolution Ogre renders at to be 800 x 600 with this call:

{CODE(wrap="1", colors="c#")}            rs.SetConfigOption("Video Mode", "800 x 600 @ 32-bit colour");
{CODE}
In practice, you should probably set the RenderSystem's resolution to be the maximum you expect the user to resize the window to. This should stop the scene from becoming pixelated when the window size is larger than the resolution Ogre is rendering at. Either that, or do not allow the user to resize the window.

!!The Go Function
The last thing we need to do is have our render loop run. Our general plan for this function is to first show the form, then start the render loop (which consists of rendering a frame and then pumping the application's event queue). We want this loop to run while mRoot != null (remember that when the form is Disposed the mRoot variable is set to null), and while mRoot.RenderOneFrame returns true. When RenderOneFrame returns false, it means that a FrameListener object has returned false, requesting that the application shut down. Here is the code to do this: (Add it to your ''Go()'' method)

{CODE(wrap="1", colors="c#")}            Show();
            while (mRoot != null && mRoot.RenderOneFrame())
                Application.DoEvents();
{CODE}
That's it. Run the application to see Ogre rendering inside of a Windows Form.

!!Pitfalls
There are a few pitfalls I have run into when embedding Ogre in Windows Forms. Hopefully this section will help you solve some of the issues you may run into.

!!!GDI and Transparency
You may place Windows.Forms controls on top of the form/control which contains Ogre. However, you cannot make those controls transparent. Doing so will produce a noticable flicker in the rendering. I have never been able to find a way around this flicker which didn't involve manually filling a backbuffer. If anyone finds a way to get around this, I'd love to hear about it.

!!!Constructors and the Forms Designer
If you subclass Form, UserControl, or some other control to house Ogre, you must be careful not to put anything in the Constructor which requires Ogre to already be set up. If you do so, this will cause Visual Studio's forms designer to not work. For example, the following code would cause the forms designer to stop working if you put it in the constructor of your class:

{CODE(wrap="1", colors="c#")}            Root root = Root.Singleton;
            NameValuePairList misc = new NameValuePairList();
            misc["externalWindowHandle"] = Handle.ToString();
            mRoot.CreateRenderWindow("Main RenderWindow", 800, 600, false, misc);
{CODE}
On the other hand, this would work fine:

{CODE(wrap="1", colors="c#")}            Root root = Root.Singleton;
            if (root != null)
            {
                NameValuePairList misc = new NameValuePairList();
                misc["externalWindowHandle"] = Handle.ToString();
                mRoot.CreateRenderWindow("Main RenderWindow", 800, 600, false, misc);
            }
{CODE}
The second chunk of code works because it does not assume that Ogre has been set up already. In practice, this will probably be a subtler bug than the code above suggests. If you create a form or control which uses Ogre (directly or indirectly) and Visual Studio's Forms Designer refuses to load it, you should try the following things:

# Clean the project, close Visual Studios, open Visual Studios, rebuild the project.
# Make sure the Ogre DLLs are in your PATH statement (see ((Mogre Basic Tutorial 0|this)) for more information]]).
# Make sure the form/control does not directly (or indirectly) use Ogre in its constructor (or in the constructors of any instance variables you have created).

!!Source Code
You can see the final state of this tutorial here: ((Mogre Tutorial - Embedding Mogre in Windows.Forms - Source))

You can also see a more fleshed out version of Ogre embedded in a form in the [http://www.idleengineer.net/tutorials/MogreFramework/MogreFramework/|MogreFramework source code].

---
Alias: (alias(Mogre_Basic_Tutorial_6))
Alias: (alias(Mogre Basic Tutorial 6))
History: Mogre Tutorial - Embedding Mogre in Windows.Forms

Source of version: 7 (current)

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